A communications network is increasingly becoming the foundation upon which many applications and services are built. The classic example of such a popular communications network is the Internet upon which, among other things, a whole new field of business termed e-commerce is based. Even within a local environment, a communications network is used for applications such as electronic mail for the dissemination of information within an organization. The quality of applications and services running over these networks is dependent on the quality of service provided by the underlying networks. This creates a need for automatic methods of measuring a network's quality. One such measure of the quality of a network is the delay in communication between a pair of devices in the network. Another measure is jitter—this measures the variance of this delay. Depending on the application, either delay measurements or jitter measurements or both may be of interest. For example, in Voice over IP (Internet Protocol) applications, not only is delay important but jitter as well—two users communicating by voice over the network should not experience a lag in communication, nor should they experience abrupt pauses in their conversation. Methods which perform these measurements can be used by a network administrator who is interested in evaluating or monitoring a network to ensure it meets the criteria for the deployment of an application over the network.
Ideally, such measurements are made remotely or from a specific fixed node in the network. This avoids the need for each node in the network to measure its own performance. Such individual piecemeal measurements would contribute to a degradation of network performance and potentially adversely affect the measurement results.
One tool which can be of use in performing such measurements is the topology of the network. Methods of determining the topology of a network are known in the art such as that described by Dawes et al in U.S. Pat. No. 5,933,416 and U.S. Pat. No. 5,926,462.
Accordingly, there is a need for methods which can be used to automatically measure network performance. Ideally, such methods would take advantage of the knowledge of the topology of the network.